Responses of tundra soil microbial communities to half a decade of experimental warming at two critical depths

Journal Article · 08 July 2019 · Proceedings of the National Academy of Sciences of the United States of America

DOI: https://doi.org/10.1073/pnas.1901307116 · OSTI ID:1532551

Johnston, Eric R. ^[1]; Hatt, Janet K. ^[2]; He, Zhili ^[3]; Wu, Liyou ^[3]; Guo, Xue  ^[4]; Luo, Yiqi ^[5]; Schuur, Edward A. G.  ^[6]; Tiedje, James M.  ^[7]; Zhou, Jizhong ^[8]; Konstantinidis, Konstantinos T. ^[9]

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1. School of Civil and Environmental Engineering, Georgia Institute of Technology, Atlanta, GA 30332,, Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37830,
2. School of Civil and Environmental Engineering, Georgia Institute of Technology, Atlanta, GA 30332,
3. Institute for Environmental Genomics, University of Oklahoma, Norman, OK 73019,, Department of Microbiology and Plant Biology, University of Oklahoma, Norman, OK 73019,
4. State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, 100091 Beijing, China,
5. Institute for Environmental Genomics, University of Oklahoma, Norman, OK 73019,, Department of Biological Sciences, Northern Arizona University, Flagstaff, AZ 86011,
6. Department of Biological Sciences, Northern Arizona University, Flagstaff, AZ 86011,
7. Center for Microbial Ecology, Michigan State University, East Lansing, MI 48824,
8. Institute for Environmental Genomics, University of Oklahoma, Norman, OK 73019,, Department of Microbiology and Plant Biology, University of Oklahoma, Norman, OK 73019,, State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, 100091 Beijing, China,, Earth Science Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720,
9. School of Civil and Environmental Engineering, Georgia Institute of Technology, Atlanta, GA 30332,, School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA 30332

Northern-latitude tundra soils harbor substantial carbon (C) stocks that are highly susceptible to microbial degradation with rising global temperatures. Understanding the magnitude and direction (e.g., C release or sequestration) of the microbial responses to warming is necessary to accurately model climate change. In this study, Alaskan tundra soils were subjected to experimental in situ warming by ∼1.1 °C above ambient temperature, and the microbial communities were evaluated using metagenomics after 4.5 years, at 2 depths: 15 to 25 cm (active layer at outset of the experiment) and 45 to 55 cm (transition zone at the permafrost/active layer boundary at the outset of the experiment). In contrast to small or insignificant shifts after 1.5 years of warming, 4.5 years of warming resulted in significant changes to the abundances of functional traits and the corresponding taxa relative to control plots (no warming), and microbial shifts differed qualitatively between the two soil depths. At 15 to 25 cm, increased abundances of carbohydrate utilization genes were observed that correlated with (increased) measured ecosystem carbon respiration. At the 45- to 55-cm layer, increased methanogenesis potential was observed, which corresponded with a 3-fold increase in abundance of a single archaeal clade of the Methanosarcinales order, increased annual thaw duration (45.3 vs. 79.3 days), and increased CH ₄ emissions. Collectively, these data demonstrate that the microbial responses to warming in tundra soil are rapid and markedly different between the 2 critical soil layers evaluated, and identify potential biomarkers for the corresponding microbial processes that could be important in modeling.

• Sponsoring Organization: USDOE
• Grant/Contract Number: SC0004601
• OSTI ID: 1532551
• Journal Information: Proceedings of the National Academy of Sciences of the United States of America, Journal Name: Proceedings of the National Academy of Sciences of the United States of America Journal Issue: 30 Vol. 116; ISSN 0027-8424
• Publisher: Proceedings of the National Academy of SciencesCopyright Statement
• Country of Publication: United States
• Language: English